Power semiconductor device and power conversion device

ABSTRACT

A semiconductor module includes a first power semiconductor element having a first surface and a second surface. The semiconductor module also includes a second power semiconductor element having a first surface and a second surface. The semiconductor module also includes first, second, third, and fourth conductor plates, and a connecting part. The connecting part is integrally formed with the second conductor plate, extends toward the third conductor plate, and is connected to the third conductor plate.

CROSS-REFERENCE TO THE APPLICATION

This application is a continuation of U.S. application Ser. No.16/017,827, filed on Jun. 25, 2018, which is a continuation of U.S.application Ser. No. 14/856,819, filed on Sep. 17, 2015, now U.S. Pat.No. 10,034,401, issued Jul. 24, 2018, which is a continuation of U.S.application Ser. No. 13/163,950, filed Jun. 20, 2011, now U.S. Pat. No.9,179,581, issued Nov. 3, 2015, which claims priority to Japanese PatentApplication No. 2010-140723, filed on Jun. 21, 2010.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a power semiconductor device includingpower semiconductor elements which perform switching operations toconvert direct-current (DC) power to alternating-current (AC) power orAC power to DC power, and relates to a power conversion device using thepower semiconductor device.

2. Description of Related Art

A power conversion unit includes a function to convert DC power suppliedfrom a DC power supply into AC power to be supplied to AC electricalload such as a rotating electrical machine or a function to convert ACpower generated by a rotating electrical machine into DC power to besupplied to a DC power supply. To serve such conversion function, thepower conversion unit includes a power semiconductor device includingpower semiconductor elements which perform switching operations. Thepower semiconductor elements repeat conduction operations andinterruption operations so that power is converted from DC power to ACpower or from AC power to DC power.

Such power semiconductor device is provided with a positiveelectrode-side terminal and a negative electrode-side terminal via whichDC power is supplied to the power semiconductor elements. PatentLiterature 1 (Japanese Laid Open Patent Publication No. 2010-110143)states a power semiconductor device in which power semiconductorelements are sealed with resin material in a state where the positiveelectrode-side terminal and the negative electrode-side terminal arelaminated and which is housed in a can-type case.

In a process of sealing power semiconductor elements, for example, it isnecessary to hold and clamp the positive electrode-side terminal and thenegative electrode-side terminal using upper and lower molds and to fillresin into the mold cavity. However, in the state where the positiveelectrode-side terminal and the negative electrode-side terminal arelaminated as stated in Patent Literature 1 described above, thelaminated area is different from other terminals in thickness, and thusover stress on the connection sections between the power semiconductorelements and the terminals and a gap between the molds may occur whenclamping. The over stress on the connection section causes the powersemiconductor elements to be damaged.

The present invention intends to reduce damage on power semiconductorelements in the manufacturing process.

SUMMARY OF THE INVENTION

A power semiconductor device according to a 1st aspect of the presentinvention includes: a plurality of power semiconductor elementsconstituting upper and lower arms of an inverter circuit; a firstsealing member having a polyhedron shape and sealing the plurality ofpower semiconductor elements; a positive electrode-side terminalconnected with any of the plurality of power semiconductor elements andprotruding from the first sealing member; a negative electrode-sideterminal connected with any of the plurality of power semiconductorelements and protruding from first sealing member; a second sealingmember sealing at least a part of the positive electrode-side terminaland at least a part of the negative electrode-side terminal; and a casein which the power semiconductor elements sealed with the first sealingmember are housed, wherein: the positive electrode-side terminal and thenegative electrode-side terminal are aligned along one surface of thefirst sealing member at their portions protruding from the first sealingmember; and the positive electrode-side terminal and the negativeelectrode-side terminal protrude in a layered state from the secondsealing member and extend out of the case.

A power semiconductor device according to a 2nd aspect of the presentinvention includes: a series circuit of a first power semiconductorelement for upper arm of an inverter and a second power semiconductorelement for lower arm of the inverter; a first sealing member sealingthe series circuit; an internal terminal protruding from the firstsealing member, for supplying DC power to the series circuit; anexternal terminal with a layer structure connected to the internalterminal; a second sealing member sealing a connection section betweenthe internal terminal and the external terminal; and a case in which theseries circuit sealed with the first sealing member and the internalterminal are housed, wherein: the external terminal is configured toextend out of the case; and magnetic fluxes are generated in directionscanceling each other out by current flowing through each layer of theexternal terminal.

According to a 3rd aspect of the present invention, in the powersemiconductor device of the 2nd aspect, it is preferred that: the caseis formed of an electrically conductive member; and an eddy current isinduced in the case by current flowing through the series circuitconnected to the internal terminal.

According to a 4th aspect of the present invention, in the powersemiconductor device of the 2nd or 3rd aspect, it is preferred that: thecase is provided with a heat dissipation surface including fins for heatdissipation outside thereof; and the power semiconductor elements,constituting the series circuit sealed with the first sealing member,are arranged opposite to the heat dissipation surface inside the case.

According to a 5th aspect of the present invention, the powersemiconductor device of any one of the 2nd through 4th aspects mayfurther include: a control terminal that transmits a drive signal of thefirst and second power semiconductor elements; and a bus bar for controlterminal connected by metallic bonding to the control terminal. In thispower semiconductor device, it is preferred that the second sealingmember further seals a connection section between the control terminaland the bus bar for control terminal.

According to a 6th aspect of the present invention, in the powersemiconductor device of the 5th aspect, it is preferred that: thecontrol terminal and the internal terminal each protrude in a samedirection from the first sealing member; the control terminal and theinternal terminal are each bent in a same direction at each of theirends; and a bent end of the control terminal and that of the internalterminal are metallically bonded with the bus bar for control terminaland the external terminal, respectively.

According to a 7th aspect of the present invention, in the powersemiconductor device of the 5th or 6th aspect, it is further preferredthat the control terminal and the internal terminal are aligned at theirportions protruding from the first sealing member.

According to an 8th aspect of the present invention, the powersemiconductor device of any one of the 2nd through 7th aspects mayfurther include: an output terminal protruding from the first sealingmember, for outputting AC power having been converted from the DC powerby the series circuit; and an output bus bar connected by metallicbonding to the output terminal. In this power semiconductor device, itis preferred that the second sealing member further seals a connectionsection between the output terminal and the output bus bar.

According to a 9th aspect of the present invention, in the powersemiconductor device of any one of the 2nd through 8th aspects, it ispreferred that: the case has one opening face; the connection sectionbetween the internal terminal and the external terminal is arrangedinward of the case from the opening face; and the external terminalextends out of the case from the opening face.

According to a 10th aspect of the present invention, the powersemiconductor device of any one of the 2nd through 9th aspects mayfurther include a supporting member supporting the external terminal. Inthis power semiconductor device, it is preferred that the supportingmember is fixed to the case.

According to an 11th aspect of the present invention, in the powersemiconductor device of any one of the 2nd through 10th aspects, it ispreferred that the second sealing member is filled in a space betweeninside of the case and the first sealing member.

A power semiconductor device according to a 12th aspect of the presentinvention includes: a first and second power semiconductor elementsconstituting an upper and lower arms, respectively, of an invertercircuit and each including a control electrode; a first and secondcontrol terminals each connected with the control electrodes included inthe first and second power semiconductor elements, respectively; apositive terminal and a negative terminal which are connected with apositive electrode side and a negative electrode side, respectively, ofa series circuit constituted with the first and second powersemiconductor elements and which supply DC power to the series circuit;and an output terminal for outputting AC power having been convertedfrom the DC power by the series circuit, wherein: the first controlterminal, the second control terminal, the positive terminal, thenegative terminal and the output terminal are each aligned; the controlelectrodes included in the first and second power semiconductor elementsare each arranged in a position shifted to either one side relative to acentral line which is perpendicular to an alignment direction of each ofthe terminals; the first and second control terminals are each arrangedon one side where the control electrodes are arranged in the first andsecond power semiconductor elements; the positive terminal is arrangedon an other side where the control electrode is not arranged in thefirst power semiconductor element; the output terminal is arranged on another side where the control electrode is not arranged in the secondpower semiconductor element; and the negative terminal is arrangedbetween the positive terminal and the second control terminal.

A power conversion device according to a 13th aspect of the presentinvention includes: a smoothing capacitor; a bridge circuit connected tothe smoothing capacitor and constituted with a plurality of powersemiconductor devices for converting from DC power to AC power or fromAC power to DC power; and a cooling flow path former through which acooling medium to cool the power semiconductor devices flows, wherein:the power semiconductor device includes: a power semiconductor element;a first sealing member sealing the power semiconductor element; aninternal terminal protruding from the first sealing member; am externalterminal connected to the internal terminal; a second sealing membersealing a connection section between the internal terminal and theexternal terminal; and a case in which the power semiconductor elementsealed with the first sealing member and the internal terminal arehoused, and the external terminal extends out.

According to a 14th aspect of the present invention, in the powerconversion device of the 13th aspect, it is preferred that: the case isprovided with a heat dissipation surface including fins for heatdissipation outside thereof; the power semiconductor element sealed withthe first sealing member is arranged opposite to the heat dissipationsurface inside the case; and the external terminal extends out.

A power conversion device according to a 15th aspect of the presentinvention includes: a smoothing capacitor; a bridge circuit connected tothe smoothing capacitor and constituted with a plurality of powersemiconductor devices for converting from DC power to AC power or fromAC power to DC power; and a cooling flow path former through which acooling medium to cool the power semiconductor devices flows, wherein:the power semiconductor device includes: a series circuit of a first andsecond power semiconductor elements for upper arm and lower arm of aninverter; a first sealing member sealing the series circuit of the firstand second power semiconductor elements; an internal terminal forsupplying DC power to the series circuit protruding from the firstsealing member; an external terminal with a layer structure connected tothe internal terminal; a second sealing member sealing a connectionsection between the internal terminal and the external terminal; and ametal case in which the power semiconductor elements sealed with thefirst sealing member and the internal terminal are housed, the externalterminal is configured to extend out; an eddy current is induced in themetal case by current flowing through the series circuit connected tothe internal terminal; and magnetic fluxes are generated in directionscanceling each other out by current flowing through each externalterminal of the layer structure.

According to a 16th aspect of the present invention, in the powersemiconductor device of the 15th aspect, it is preferred that: thesmoothing capacitor includes: a plurality of capacitor cells arranged inthe smoothing capacitor and connected in parallel; a power supplyterminal for connection to a DC power supply; and a plurality ofterminals with a layer structure connected with the external terminal ofthe power semiconductor device; and the terminals with the layerstructure of the smoothing capacitor are each connected to the externalterminal of the power semiconductor device.

According to the present invention, the power semiconductor elementswill be prevented from being damaged in the manufacturing process ofpower modules.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing control blocks of a hybrid vehicle.

FIG. 2 is a diagram explaining the electrical circuit structure of aninverter circuit 140.

FIG. 3 is an external perspective view of a power conversion device 200.

FIG. 4 is an external perspective view of the power conversion device200.

FIG. 5 is an exploded perspective view of the power conversion device200.

FIG. 6 is an exploded perspective view of the power conversion device200.

FIG. 7 is an exploded perspective view of the power conversion device200.

FIG. 8 is an external perspective view of a flow path former 12 to whichpower modules 300U to 300W, a capacitor module 500, and a bus barassembly 800 are assembled.

FIG. 9 is a view showing the flow path former 12 without the bus barassembly 800.

FIG. 10 is a perspective view of the flow path former 12.

FIG. 11 is an exploded perspective view of the flow path former 12 seenfrom behind.

FIGS. 12A and 12B are views showing the power module according to anembodiment of the present invention, of which FIG. 12A is a perspectiveview and FIG. 12B is a sectional view.

FIGS. 13A, 13B, and 13C are views showing the power module with screwsand a second sealing resin not illustrated, of which FIG. 13A is aperspective view, FIG. 13B is a sectional view, and FIG. 13C is asectional view before a curved portion of a case is deformed.

FIGS. 14A and 14B are views showing the power module with the case notillustrated, of which FIG. 14A is a perspective view and FIG. 14B is asectional view.

FIG. 15 is a perspective view of the power module with a first sealingresin and a wiring insulation section not illustrated.

FIGS. 16A and 16B are views showing an ancillary molded body, of whichFIG. 16A is a perspective view and FIG. 16B is a sectional view.

FIG. 17 is a view for explaining an assembly process of a module primaryseal body.

FIG. 18 is a view for explaining the assembly process of the moduleprimary seal body.

FIG. 19 is a view for explaining the assembly process of the moduleprimary seal body.

FIG. 20 is a view for explaining the assembly process of the moduleprimary seal body.

FIG. 21 is a view for explaining the assembly process of the moduleprimary seal body.

FIGS. 22A and 22B are views for explaining a transfer molding process ofthe first sealing resin, of which FIG. 22A is a vertical sectional viewbefore clamping and FIG. 22B is a vertical sectional view afterclamping.

FIG. 23 is a view showing an arrangement relationship between controlelectrodes of the power semiconductor element and each of the terminals.

FIG. 24 is a view showing a variation which is provided with a stressrelief section on a conductor plate of a DC negative wiring side.

FIG. 25 is a diagram showing the internal circuit structure of the powermodule according to an embodiment of the present invention.

FIGS. 26A and 26B are figures for explaining reduction of inductance inthe power module according to the embodiment of the present invention.

FIG. 27 is an external perspective view of the capacitor module 500.

FIG. 28 is a perspective view of the bus bar assembly 800.

FIG. 29 is a view showing the flow path former 12 on which the powermodules 300U to 300W and the capacitor module 500 are mounted.

FIG. 30 is a horizontal sectional view of the flow path former 12.

FIG. 31 is a schematic view for explaining the arrangement of the powermodules 300U to 300W.

FIG. 32 is a view showing a cross section of the power conversion device200.

FIG. 33 is a view explaining a layout of the power conversion device 200which is mounted on a vehicle.

FIG. 34 is a view showing a variation of the arrangement of the powermodules in the present invention.

FIG. 35 is a view showing a variation of the arrangement of the powermodules in the present invention.

FIG. 36 is a view showing a variation of the arrangement of the powermodules in the present invention.

FIG. 37 is a sectional view of the flow path former 12 according to thepresent embodiment.

FIG. 38 is a view showing a variation with a divided DC negative wiring.

FIG. 39 is a diagram for explaining an assembly process of the moduleprimary seal body according to a variation.

FIG. 40 is a diagram for explaining an assembly process of the moduleprimary seal body according to a variation.

FIG. 41 is a diagram for explaining an assembly process of the moduleprimary seal body according to a variation.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the embodiments stated below, in addition to the problems and theadvantageous effects stated as problems to be solved by the inventionand advantageous effects of the invention respectively, problems aresolved and advantageous effects are achieved so as to make a desiredproduct. These will be explained in the following embodiments.

An embodiment of the present invention will now be explained withreference to the drawings. FIG. 1 is a diagram showing control blocks ofa hybrid electric vehicle (hereinafter referred to as “HEV”). An engineEGN and a motor generator MG1 generate torque for driving a vehicle. Inaddition, the motor generator MG1 has a function not only to generaterotational torque but also to convert mechanical energy applied fromoutside to the motor generator MG1 into electric power.

The motor generator MG1 is, for example, a synchronous machine or aninduction machine, and, as described above, works as a motor or anelectric generator depending upon the operational method. When mountedon a vehicle, the motor generator MG1 is preferred to be small in sizeand high in power, and thus a permanent magnet type synchronous electricmachine which uses a magnet such as neodymium is appropriate. Inaddition, a permanent magnet type synchronous electric machine isexcellent for a vehicle also because its rotor generates less heat thanthat of an induction electric machine.

Output torque on the output side of the engine EGN is transmitted to themotor generator MG1 through a power distribution mechanism TSM.Rotational torque from the power distribution mechanism TSM orrotational torque generated by the motor generator MG1 is transmitted towheels through a transmission TM and a differential gear DEF. In aregenerative braking operation, on the other hand, rotational torque istransmitted from the wheels to the motor generator MG1. The motorgenerator MG1 generates AC power based upon the rotational torquesupplied from the wheels. The generated AC power is, as described later,converted into DC power by the power conversion device 200 and charges ahigh-voltage battery 136. The electric power charged at the battery 136is used again as travel energy.

Next, the power conversion device 200 will be explained. The invertercircuit 140 is electrically connected with the battery 136 through a DCconnector 138. Electric power is transferred between the battery 136 andthe inverter circuit 140. When the motor generator MG1 operates as amotor, the inverter circuit 140 generates AC power based upon DC powersupplied from the battery 136 through the DC connector 138 and suppliesit to the motor generator MG1 through an AC terminal 188. The structureconstituted with the motor generator MG1 and the inverter circuit 140operates as a first electric motor generator unit.

It is to be noted that, in the present embodiment, the first electricmotor generator unit operates on electric power of the battery 136 as anelectric motor unit so as to drive the vehicle only on power of themotor generator MG1. In addition, in the present embodiment, the firstelectric motor generator unit operates as a power generation unit onpower of an engine 120 or power from the wheels so as to generateelectric power, thereby charging the battery 136.

Moreover, although not shown in FIG. 1, the battery 136 is also used asa power source for driving a motor for auxiliaries. The motor forauxiliaries is, for example, a motor to drive the compressor of the airconditioner or a motor to drive a hydraulic pump for control. DC poweris supplied from the battery 136 to a power module for auxiliaries andthe power module for auxiliaries generates AC power and supplies it tothe motor for auxiliaries. The power module for auxiliaries, havingbasically the same circuit configuration and functions as those theinverter circuit 140 has, controls the phase, frequency, and electricpower of AC to be supplies to the motor for auxiliaries. It is to benoted that the power conversion device 200 includes the capacitor module500 for smoothing DC power to be supplied to the inverter circuit 140.

The power conversion device 200 includes a communication connector 21for receiving an instruction from a higher-order control device ortransmitting data indicating a status to the higher-order controldevice. In the power conversion device 200, a control circuit 172calculates a control amount of the motor generator MG1 based upon aninstruction to be input from the connector 21 and in addition calculateswhether to operate as a motor or to operate as an electric generator.Based upon those calculation results, the control circuit 172 generatescontrol pulses and supplies the control pulses to a driver circuit 174.Based upon the supplied control pulses, the driver circuit 174 generatesdrive pulses for controlling the inverter circuit 140.

Next, the structure of the electrical circuit of the inverter circuit140 will be explained with reference to FIG. 2. It is to be noted thatin the following example an insulated gate bipolar transistor is used asa semiconductor element, which is abbreviated to an IGBT hereinafter. Aseries circuit 150 of upper and lower arms is constituted with an IGBT328 and a diode 156, which operate as the upper arm, and an IGBT 330 anda diode 166, which operate as the lower arm. The inverter circuit 140includes this series circuit 150 corresponding to each of three phases,i.e., a U phase, a V phase, and a W phase, of the AC power to be output.

In this embodiment, these three phases correspond to each phase windingof the three phases of an armature winding of the motor generator MG1.The series circuit 150 of upper and lower arms of each of the threephases outputs AC current from an intermediate electrode 169, which isthe midpoint of the series circuit. This intermediate electrode 169 isconnected through an AC terminal 159 and an AC terminal 188 with AC busbars 802 and 804 to be described below, which are AC power lines to themotor generator MG1.

A collector electrode 153 of the IGBT 328 of the upper arm iselectrically connected through a positive terminal 157 to a capacitorterminal 506 on the positive electrode side of the capacitor module 500.In addition, an emitter electrode of the IGBT 330 of the lower arm iselectrically connected through a negative terminal 158 to a capacitorterminal 504 on the negative electrode side of the capacitor module 500.

As described above, the control circuit 172 receives a controlinstruction from the higher-order control device through the connector21. Then, based upon this, the control circuit 172 generates the controlpulses, which are control signals for controlling the IGBT 328 and theIGBT 330 constituting the upper arm or the lower arm of the seriescircuit 150 of each of the phases constituting the inverter circuit 140,and supplies the control pulses to the driver circuit 174.

The driver circuit 174, based upon the above control pulses, suppliesthe drive pulses for controlling the IGBT 328 and the IGBT 330constituting the upper arm or the lower arm of the series circuit 150 ofeach of the phases to the IGBT 328 and the IGBT 330 of each of thephases. The IGBT 328 and the IGBT 330, based upon the drive pulses fromthe driver circuit 174, carry out a conduction or interruption operationto convert the DC power supplied from the battery 136 into three-phaseAC power. This converted electric power is supplied to the motorgenerator MG1.

The IGBT 328 includes the collector electrode 153, an emitter electrode155 for signals, and a gate electrode 154. The IGBT 330 includes thecollector electrode 163, an emitter electrode 165 for signals, and agate electrode 164. The diode 156 is electrically connected between thecollector electrode 153 and the emitter electrode 155. The diode 166 iselectrically connected between the collector electrode 163 and theemitter electrode 165.

A metal-oxide semiconductor field-effect transistor (hereinafterabbreviated to MOSFET) may be used as a power semiconductor element forswitching. In this case, the diode 156 and the diode 166 becomeunnecessary. As a power semiconductor element for switching, an IGBT issuitable for relatively high DC voltage and a MOSFET is suitable forrelatively low DC voltage.

The capacitor module 500 includes the positive electrode-side capacitorterminal 506, the negative electrode-side capacitor terminal 504, apositive electrode-side power supply terminal 509, and a negativeelectrode-side power supply terminal 508. High-voltage DC power issupplied from the battery 136 through the DC connector 138 to thepositive electrode-side power supply terminal 509 and the negativeelectrode-side power supply terminal 508, and then supplied from thepositive electrode-side capacitor terminal 506 and the negativeelectrode-side capacitor terminal 504 of the capacitor module 500 to theinverter circuit 140.

On the other hand, the DC power having been converted from AC power bythe inverter circuit 140 is supplied from the positive electrode-sidecapacitor terminal 506 and the negative electrode-side capacitorterminal 504 to the capacitor module 500, supplied from the positiveelectrode-side power supply terminal 509 and the negative electrode-sidepower supply terminal 508 through the DC connector 138 to the battery136, and then stored in the battery 136.

The control circuit 172 includes a microcomputer for performingcalculation processing of switching timing of the IGBT 328 and the IGBT330. Input information to the microcomputer includes a target torquevalue required to the motor generator MG1, a current value supplied fromthe series circuit 150 to the motor generator MG1, and a magnetic poleposition of the rotor of the motor generator MG1.

The target torque value is based upon an instruction signal having beenoutput from a higher-order control device not shown in the figures. Thecurrent value is detected based upon a detection signal by a currentsensor 180. The magnetic pole position is detected based upon adetection signal having been output from a rotating magnetic pole sensor(not shown in the figures) such as a resolver provided to the motorgenerator MG1. While in the present embodiment, the explanation is madeon an example in which the current sensor 180 detects current values forthree phases, the current sensor 180 may be arranged to detect currentvalues for two phases and obtains currents for three phases oncalculation.

The microcomputer in the control circuit 172 calculates currentinstruction values of a d axis and a q axis of the motor generator MG1based upon the target torque value, calculates voltage instructionvalues of the d axis and the q axis based upon differences between thecalculated current instruction values of the d axis and the q axis andthe detected current values of the d axis and the q axis, and thenconverts the calculated voltage instruction values of the d axis and theq axis into voltage instruction values of the U phase, the V phase, andthe W phase based upon the detected magnetic pole position. Then, themicrocomputer generates a pulse-like modulated wave based uponcomparison between a fundamental wave (sine wave), which is based uponthe voltage instruction values of the U phase, the V phase, and the Wphase, and a carrier wave (triangle wave), and then outputs thisgenerated modulated wave to the driver circuit 174 as a PWM (pulse-widthmodulation) signal.

When driving the lower arm, the driver circuit 174 outputs a drivesignal, which is an amplified PWM signal, to the gate electrode of theIGBT 330 of the corresponding lower arm. When driving the upper arm, thedriver circuit 174 shifts the reference potential level of the PWMsignal to the reference potential level of the upper arm, amplifies thePWM signal, and then outputs it as a drive signal to the gate electrodeof the IGBT 328 of the corresponding upper arm.

In addition, the microcomputer in the control circuit 172 performsabnormality detection (over current, over voltage, over temperature, andthe like) so as to protect the series circuit 150. For this purpose,sensing information has been input to the control circuit 172. Forexample, information of current flowing through the emitter electrode ofeach of the IGBT 328 and the IGBT 330 is input from the emitterelectrode 155 for signals and the emitter electrode 165 for signals ofeach of the arms to a corresponding drive unit (IC). This causes each ofthe drive units (IC) to perform over current detection and, if overcurrent is detected, to stop switching operations of the correspondingIGBT 328 and IGBT 330 and protect the corresponding IGBT 328 and IGBT330 from the over current.

Information of temperature of the series circuit 150 is input from atemperature sensor (not shown in the figures) provided to the seriescircuit 150 to the microcomputer. In addition, information of DCpositive electrode-side voltage at the series circuit 150 is input tothe microcomputer. Based upon those pieces of information, themicrocomputer performs over temperature detection and over voltagedetection and, if over temperature or over voltage is detected, stopsall the switching operations of the IGBT 328 and the IGBT 330.

FIGS. 3 and 4 are external perspective views of the power conversiondevice 200 as an embodiment according to the present invention. FIG. 4shows a state in which an AC connector 187 and the DC connector 138 areremoved. The power conversion device 200 of the present embodiment isprovided in a rectangular planar shape which is substantially square soas to be small in size and has an effect of facilitating mounting to thevehicle. A reference numeral 8 denotes a lid, 10 a housing, 12 a flowpath former, 13 a cooling medium inlet pipe, 14 an outlet pipe, and 420a lower cover. The connector 21 is a connector for signals provided forexternal connection.

The lid 8 is fixed to an upper opening of the housing 10 in whichcircuit components constituting the power conversion device 200 arehoused. The flow path former 12, which is fixed to a lower part of thehousing 10, holds the power modules 300 and the capacitor module 500,which are described later, and cools them by a cooling medium. Sincewater, for instance, is most commonly used as a cooling medium, theexplanation will hereinafter be made with cooling water as an example.An inlet pipe 13 and an outlet pipe 14 are provided on one lateralsurface of the flow path former 12, and cooling water supplied from theinlet pipe 13 flows into a flow path 19, described later, in the flowpath former 12 and is released from the outlet pipe 14.

An AC interface 185 on which the AC connector 187 is mounted and a DCinterface 137 on which the DC connector 138 is mounted are provided on alateral surface of the housing 10. The AC interface 185 is provided onthe lateral surface on which the pipes 13 and 14 are provided, and an ACwiring 187 a of the AC connector 187 mounted on the AC interface 185extends downward through between the pipes 13 and 14. The DC interface137 is provided on the lateral surface adjacent to the lateral surfaceon which the AC interface 185 is provided, and a DC wiring 138 a of theDC connector 138 mounted on the DC interface 137 also extends downwardthe power conversion device 200.

Since the AC interface 185 and the pipes 13 and 14 are thus arranged onthe side of a same lateral surface 12 d and the AC wiring 187 a is drawndownward as it passes through between the pipes 13 and 14, the spaceoccupied by the pipes 13 and 14, the AC connector 187, and the AC wiring187 a is reduced in size, thereby preventing the whole device frombecoming large in size. In addition, since the AC wiring 187 a is drawndownward with respect to the pipes 13 and 14, the AC wiring 187 a iseasily wired, thereby improving productivity.

FIG. 5 is a view showing a state in which the lid 8, the DC interface137, and the AC interface 185 are removed from the power conversiondevice 200 shown in FIG. 4. One lateral surface of the housing 10 isprovided with an opening 10 a through which the AC interface 185 isfixed and another lateral surface adjacent thereto is provided with anopening 10 b through which the DC interface 137 is fixed. From theopening 10 a, three AC bus bars 802, i.e., a U phase AC bus bar 802U, aV phase AC bus bar 802V, and a W phase AC bus bar 802W, protrude, andfrom the opening 10 b the DC power supply terminals 508 and 509protrude.

FIG. 6 is a view showing a state in which the housing 10 is removed fromthe flow path former 12 in FIG. 5. The housing 10 is sectioned by adividing wall 10 c into two housing spaces, i.e., an upper housing spaceand a lower housing space. A control circuit board 20, to which theconnector 21 is fixed, is housed in the upper housing space and a drivercircuit board 22 and the bus bar assembly 800, which will be describedlater, are housed in the lower housing space (refer to FIG. 7). Thecontrol circuit board 20 is mounted with the control circuit 172 shownin FIG. 2, and the driver circuit board 22 is mounted with the drivercircuit board 174. The control circuit board 20 and the driver circuitboard 22 are connected through a flat cable not shown in the figure(refer to FIG. 7 described later), and the flat cable is drawn from thelower housing space to the upper housing space via a slit-like opening10 d formed on the dividing wall 10 c.

FIG. 7 is an exploded perspective view of the power conversion device200. Inside the lid 8, i.e., in the upper housing space of the housing10, the control circuit board 20 on which the control circuit 172 ismounted as described above is arranged. The lid 8 is provided with anopening (not shown in the figure) for the connector 21. Low-voltage DCpower to operate the control circuit in the power conversion device 200is supplied from the connector 21.

The flow path former 12 is provided with a flow path through whichcooling water having flowed in from the inlet pipe 13 flows, which willbe described in detail later. The flow path is formed in a U shape sothat the cooling water flows along three lateral surfaces of the flowpath former 12. The cooling water, having flowed in from the inlet pipe13, flows into the flow path from an end of the U shaped flow path,flows through the flow path, and then flows out from the outlet pipe 14,which is connected to the other end of the flow path.

On the upper surface of the flow path, three openings 402 a to 402 c areformed, from which the power modules 300U, 300V, and 300W, which areprovided with the built-in series circuits 150 (refer to FIG. 1), areinserted into the flow path. The power module 300U is provided with thebuilt-in U phase series circuit 150, the power module 300V is providedwith the built-in V phase series circuit 150, and the power module 300Wis provided with the built-in W phase series circuit 150. The powermodules 300U to 300W have the same structure and the same externalshape. The openings 402 a to 402 c are covered with flange sections ofthe inserted power modules 300U to 300W.

The flow path former 12 is provided with a housing space 405 for housingelectric components as surrounded by the U shaped flow path. In thepresent embodiment, the capacitor module 500 is housed in the housingspace 405. The capacitor module 500, housed in the housing space 405, iscooled by the cooling water flowing through the flow path. Above thecapacitor module 500, the bus bar assembly 800, on which the AC bus bars802U to 802W are mounted, is arranged. The bus bar assembly 800 is fixedon the upper surface of the flow path former 12. A current sensor module180 is fixed on the bus bar assembly 800.

The driver circuit board 22 is fixed to supporting members 807 a,provided on the bus bar assembly 800, so as to be arranged above the busbar assembly 800. As described above, the control circuit board 20 andthe driver circuit board 22 are connected through a flat cable. The flatcable is drawn from the lower housing space to the upper housing spacethrough the slit-like opening 10 d, formed on the dividing wall 10 c.

In this manner, the power modules 300U to 300W, the driver circuit board22, and the control circuit board 20 are hierarchically arranged in theheight direction and the control circuit board 20 is arranged at afarthest place from the high-rate power modules 300U to 300W, therebyreducing contamination of switching noise and the like to the controlcircuit board 20. In addition, since the driver circuit board 22 and thecontrol circuit board 20 are arranged in different housing spacessectioned by the dividing wall 10 c, the dividing wall 10 c functions asan electromagnetic shield, thereby reducing noise contaminated from thedriver circuit board 22 to the control circuit board 20. It is to benoted that the housing 10 is formed of metal material such as aluminium.

In addition, since the control circuit board 20 is fixed on the dividingwall 10 c, which is integrally provided with the housing 10, themechanical resonance frequency of the control circuit board 20 becomeshigher against external vibration. For this reason, the power conversiondevice 200 is less susceptible to vibration from the vehicle side,thereby improving reliability.

The flow path former 12 and the power modules 300U to 300W, thecapacitor module 500, and the bus bar assembly 800, which are fixed onthe flow path former 12, will now be explained in detail further. FIG. 8is an external perspective view of the flow path former 12, to which thepower modules 300U to 300W, the capacitor module 500, and the bus barassembly 800 are assembled. In addition, FIG. 9 shows a state in whichthe bus bar assembly 800 is removed from the flow path former 12. Thebus bar assembly 800 is bolted to the flow path former 12.

At first, the flow path former 12 will be explained with reference toFIGS. 10 and 11. FIG. 10 is a perspective view of the flow path former12 and FIG. 11 is an exploded perspective view of the flow path former12 seen from behind. As shown in FIG. 10, the flow path former 12 isprovided in a rectangular planar shape which is substantially square andthe lateral surface 12 d thereof is provided with the inlet pipe 13 andthe outlet pipe 14. It is to be noted that the lateral surface 12 d isformed in a stepped manner at the portion on which the pipes 13 and 14are provided. As shown in FIG. 11, the flow path 19 is formed into a Ushape along the other three lateral surfaces 12 a to 12 c. Then, theback side of the flow path former 12 is provided with an unsectioned Ushaped opening 404 having substantially the same shape as across-sectional shape of the flow path 19. The opening 404 is coveredwith the U shaped lower cover 420. A sealing member 409 a is providedbetween the lower cover 420 and the flow path former 12, therebyproviding an airtight seal.

The flow path 19, provided in a U shape, is divided into three flow pathsections 19 a, 19 b, and 19 c depending upon the direction of the flowof cooling water. The first flow path section 19 a is provided along thelateral surface 12 a in a position opposite to the lateral surface 12 don which the pipes 13 and 14 are provided, the second flow path section19 b is provided along the lateral surface 12 b adjacent to one side ofthe lateral surface 12 a, and the third flow path section 19 c isprovided along the lateral surface 12 c adjacent to the other side ofthe lateral surface 12 a, as described later in detail. Cooling waterflows in from the inlet pipe 13 to the flow path section 19 b, flowsthrough in order of the flow path section 19 b, the flow path section 19a, and the flow path section 19 c as indicated by the dashed arrow, andthen flows out from the outlet pipe 14.

As shown in FIG. 10, on the upper surface side of the flow path former12, a rectangular opening 402 a, parallel to the lateral surface 12 a,is formed in a position opposite to the flow path section 19 a, arectangular opening 402 b, parallel to the lateral surface 12 b, isformed in a position opposite to the flow path section 19 b, and arectangular opening 402 c, parallel to the lateral surface 12 c, isformed in a position opposite to the flow path section 19 c. Throughthese openings 402 a to 402 c, the power modules 300U to 300W areinserted into the flow path 19.

As shown in FIG. 11, raised portions 406 protruding downward the flowpath 19 are formed on the lower cover 420 in a position opposite to eachof the openings 402 a to 402 c described above. These raised portions406 are recesses if seen from the flow path 19 side, and lower endportions of the power modules 300U to 300W inserted through the openings402 a to 402 c fit into these recesses. Since the flow path former 12 isformed so that the opening 404 is opposite to the openings 402 a to 402c, it is easily manufactured by aluminium casting.

As shown in FIG. 10, the flow path former 12 is provided with therectangular housing space 405 formed so that its three sides aresurrounded by the flow path 19. The capacitor module 500 is housed inthe housing space 405. Since the housing space 405 surrounded by theflow path 19 is provided in a rectangular shape, the capacitor module500 is provided in a rectangular shape, thereby improving theproductivity of the capacitor module 500.

The structure of the power modules 300U to 300W and power modules 301Uto 301W, which are used in the inverter circuit 140, will be explainedin detail with reference to FIG. 12A to FIG. 26B. The power modules 300Uto 300W and the power modules 301U to 301W each have the same structureand hence the structure of the power module 300U will be explained as arepresentative thereof. It is to be noted that in FIG. 12A to FIG. 26B,a signal terminal 325U corresponds to the gate electrode 154 and theemitter electrode 155 for signals, disclosed in FIG. 2, and a signalterminal 325L corresponds to the gate electrode 164 and the emitterelectrode 165, disclosed in FIG. 2. In addition, a DC positive terminal315B is identical to the positive terminal 157, disclosed in FIG. 2, anda DC negative terminal 319B is identical to the negative terminal 158,disclosed in FIG. 2. In addition, an AC terminal 320B is the same as theAC terminal 159, disclosed in FIG. 2.

FIG. 12A is a perspective view of the power module 300U of the presentembodiment. FIG. 12B is a sectional view of the power module 300U of thepresent embodiment being cut on a cross section D and seen from adirection E.

FIGS. 13A, B, and C are views showing the power module 300U with a screw309 and a second sealing resin 351 removed from the configuration in thestate shown in FIGS. 12A and 12B for better understanding. FIG. 13A is aperspective view and FIG. 13B is a sectional view of the power module300U of the present embodiment being cut on the cross section D and seenfrom the direction E as in FIG. 12B. In addition, FIG. 13C shows asectional view before pressure is applied to fins 305 so that curvedportions 304A are deformed.

FIGS. 14A and 14B are views showing the power module 300U with a modulecase 304 further removed from the configuration in the state shown inFIGS. 13A and 13B. FIG. 14A is a perspective view and FIG. 14B is asectional view of the power module 300U of the present embodiment beingcut on the cross section D and seen from the direction E as in FIG. 12Band FIG. 13B.

FIG. 15 is a perspective view of the power module 300U with a firstsealing resin 348 and a wiring insulation section 608 further removedfrom the configuration in the state shown in FIGS. 14A and 14B.

FIGS. 16A and 16B are views showing an ancillary molded body 600 of thepower module 300U. FIG. 16A is a perspective view and FIG. 16B is asectional view of the ancillary molded body 600 being cut on the crosssection D and seen from the direction E as in FIG. 12B, FIG. 13B, andFIG. 14B.

The power semiconductor elements (the IGBT 328, the IGBT 330, the diode156, and the diode 166) constituting the series circuit 150 of the upperand lower arms are, as shown in FIGS. 14A, 14B, and 15, sandwiched fromthe both sides and fixed by a conductor plate 315 and a conductor plate318 or a conductor plate 320 and a conductor plate 319. The conductorplate 315 and the like are sealed by the first sealing resin 348 in astate where their heat dissipation surfaces are exposed, and aninsulation sheet 333 is thermo-compression bonded to the heatdissipation surfaces. The first sealing resin 348 is provided in apolyhedron shape (here, substantially rectangular solid shape) as shownin FIGS. 14A and 14B.

A module primary seal body 302 sealed by the first sealing resin 348 isinserted into the module case 304 and thermo-compression bonded onto theinner surface of the module case 304, which is a can-type cooler, acrossthe insulation sheet 333. Here, the can-type cooler is a cylinder shapedcooler having an insertion slot 306 on one side and a bottom on theother side. An air gap remaining inside the module case 304 is filledwith the second sealing resin 351.

The module case 304 is formed of an electrically conductive member suchas aluminium alloy material (Al, AlSi, Al SiC, Al—C, and the like) andintegrally formed seamlessly. The module case 304 is configured not toinclude an opening other than the insertion slot 306, and the insertionslot 306 is surrounded by a flange 304B around the outer circumferencethereof. In addition, as shown in FIG. 12A, a first heat dissipationsurface 307A and a second heat dissipation surface 307B, which have alarger surface than another surface, are arranged in a state where theyare opposite to each other, and each of the power semiconductor elements(the IGBT 328, the IGBT 330, the diode 156, and the diode 166) isarranged opposite to these heat dissipation surfaces. The three surfacesconnected to the first heat dissipation surface 307A and the second heatdissipation surface 307B, which are opposite to each other, constitute asurface sealed in a width smaller than the first heat dissipationsurface 307A and the second heat dissipation surface 307B, and theinsertion slot 306 is formed on the surface of the remaining one side.The module case 304 may not be provided in an accurately rectangularshape but may be round in corners as shown in FIG. 12A.

Since the use of a metal case with such shape enables sealing to acooling medium to be ensured at the flange 304B even if the module case304 is inserted into the flow path 19 through which a cooling mediumsuch as water or oil is flowing, the cooling medium is prevented by asimple structure from entering inside the module case 304. In addition,the fins 305 are formed uniformly on each of the first heat dissipationsurface 307A and the second heat dissipation surface 307B, opposite toeach other. In addition, the extremely thin curved portions 304A areformed on the outer circumference of the first heat dissipation surface307A and the second heat dissipation surface 307B. The curved portions304A are made extremely thin to an extent where they are easily deformedby applying pressure to the fins 305, thereby improving the productivityafter the module primary seal body 302 is inserted.

The conductor plate 315 and the like are thermo-compression bonded ontothe inner wall of the module case 304 through the insulation sheet 333as described above so as to allow the air gap between the conductorplate 315 and the like and the inner wall of the module case 304 to bereduced, thereby transmitting generated heat at the power semiconductorelements to the fins 305 efficiently. In addition, the insulation sheet333 is made thick and flexible to some extent so that the generatedthermal stress is absorbed in the insulation sheet 333, and thus thepower semiconductor device is excellent for use in a power conversiondevice for a vehicle with severe temperature changes.

A metal DC positive wiring 315A and a metal DC negative wiring 319A,which are to be electrically connected with the capacitor module 500,are provided outside the module case 304 and end sections thereof areprovided with the DC positive terminal 315B (157) and the DC negativeterminal 319B (158), respectively. In addition, a metal AC wiring 320Afor supplying AC power to the motor generator MG1 is provided and itsend is provided with the AC terminal 320B (159). In the presentembodiment, as shown in FIG. 15, the DC positive wiring 315A isconnected with the conductor plate 315, the DC negative wiring 319A isconnected with the conductor plate 319, and the AC wiring 320A isconnected with the conductor plate 320.

In addition, metal signal wirings 324U and 324L, which are to beelectrically connected with the driver circuit 174, are provided outsidethe module case 304, their end sections are provided with the signalterminal 325U (154, 155) and the signal terminal 325L (164, 165),respectively. In the present embodiment, as shown in FIG. 15, the signalwiring 324U is connected with the IGBT 328 and the signal wiring 324L isconnected with the IGBT 328.

The DC positive wiring 315A, the DC negative wiring 319A, the AC wiring320A, the signal wiring 324U, and the signal wiring 324L are integrallyformed as the ancillary molded body 600 in a state where they areinsulated from one another by the wiring insulation section 608 formedof resin material. The wiring insulation section 608 also acts as asupporting member for supporting each wiring, and thus thermosettingresin or thermoplastic resin, having insulation properties, isappropriate for the resin material used for the wiring insulationsection 608. This ensures insulation among the DC positive wiring 315A,the DC negative wiring 319A, the AC wiring 320A, the signal wiring 324Uand the signal wiring 324L, thereby enabling high density wiring. Theancillary molded body 600 is metallically bonded with the module primaryseal body 302 at a connection section 370 before fixed to the modulecase 304 with the screw 309 passing through a screw hole provided on thewiring insulation section 608. The metal bonding of the module primaryseal body 302 with the ancillary molded body 600 at the connectionsection 370 may be TIG-welded, for instance.

The DC positive wiring 315A and the DC negative wiring 319A are layeredin a state where they are opposite to each other across the wiringinsulation section 608, thereby constituting a shape extendingsubstantially in parallel. Such arrangement and shape causes theinstantaneous currents to flow against and in the opposite direction toeach other during switching operations of the power semiconductorelements. This has an effect to cause the magnetic fields generated bythe current to cancel each other out, thereby allowing reduction ofinductance. It is to be noted that the AC wiring 320A and the signalterminals 325U and 325L also extend in the same direction as the DCpositive wiring 315A and the DC negative wiring 319A.

The connection section 370, at which the module primary seal body 302and the ancillary molded body 600 are metallically bonded, is sealed inthe module case 304 with the second sealing resin 351. This stablyensures a necessary insulation distance between the connection section370 and the module case 304, thereby achieving reduction in size of thepower module 300U compared to one that is not sealed.

As shown in FIG. 15 and FIGS. 16A and 16B, on the ancillary module 600side of the connection section 370, an ancillary module-side DC positiveconnection terminal 315C, an ancillary module-side DC negativeconnection terminal 319C, an ancillary module-side AC connectionterminal 320C, an ancillary module-side signal connection terminal 326U,and an ancillary module-side signal connection terminal 326L arealigned. On the module primary seal body 302 side of the connectionsection 370, on the other hand, an element-side DC positive connectionterminal 315D, an element-side DC negative connection terminal 319D, anelement-side AC connection terminal 320D, an element-side signalconnection terminal 327U, and an element-side signal connection terminal327L are aligned along one surface of the first sealing resin 348provided in a polyhedron shape. In this manner, each of the terminals isconfigured to be aligned at the connection section 370, therebyfacilitating manufacturing of the module primary seal body 302 bytransfer molding.

Here, a description will be given on the position relationship of eachof the terminals with portions which extend outward from the firstsealing resin 348 of the module primary seal body 302 regarded as oneterminal for each type. In the explanation below, a terminal constitutedwith the DC positive wiring 315A (inclusive of the DC positive terminal315B and the ancillary module-side DC positive connection terminal 315C)and the element-side DC positive connection terminal 315D will bereferred to as a positive electrode-side terminal, a terminalconstituted with the DC negative wiring 319A (inclusive of the DCnegative terminal 319B and the ancillary module-side DC negativeconnection terminal 319C) and the element-side DC negative connectionterminal 315D will be referred to as a negative electrode-side terminal,a terminal constituted with the AC wiring 320A (inclusive of the ACterminal 320B and the ancillary module-side AC connection terminal 320C)and the element-side AC connection terminal 320D will be referred to asan output terminal, a terminal constituted with the signal wiring 324U(inclusive of the signal terminal 325U and the ancillary module-sidesignal connection terminal 326U) and the element-side signal connectionterminal 327U will be referred to as a signal terminal for the upperarm, and a terminal constituted with the signal wiring 324L (inclusiveof the signal terminal 325L and the ancillary module-side signalconnection terminal 326L) and the element-side signal connectionterminal 327L will be referred to as a signal terminal for the lowerarm.

Each of the above terminals protrudes from the first sealing resin 348and the second sealing resin 351 through the connection section 370, andeach of the protruding portions from the first sealing resin 348 (theelement-side DC positive connection terminal 315D, the element-side DCnegative connection terminal 319D, the element-side AC connectionterminal 320D, the element-side signal connection terminal 327U, and theelement-side signal connection terminal 327L) is aligned along onesurface of the first sealing resin 348 provided in the polyhedron shapedescribed above. In addition, the positive electrode-side terminal andthe negative electrode-side terminal protrude from the second sealingresin 351 in a layered state and extend out of the module case 304. Suchconfiguration will prevent over stress on the connection section of thepower semiconductor elements with the terminal and a gap in mold fromoccurring at the time of clamping when the power semiconductor elementsare sealed with the first sealing resin 348 so as to manufacture themodule primary seal body 302. In addition, magnetic fluxes in directionscanceling each other out are generated by the currents of oppositedirections flowing through the layered positive electrode-side terminaland negative electrode-side terminal, thereby achieving reduction ofinductance.

On the ancillary module 600 side, the ancillary module-side DC positiveconnection terminal 315C and the ancillary module-side DC negativeconnection terminal 319C are formed at the end sections of the DCpositive wiring 315A and the DC negative wiring 319A on the oppositeside of the DC positive terminal 315B and the DC negative terminal 319B,respectively. In addition, the ancillary module-side AC connectionterminal 320C is formed at the end section of the AC wiring 320A on theopposite side of the AC terminal 320B. The ancillary module-side signalconnection terminals 326U and 326L are formed at the end sections of thesignal wirings 324U and 324L on the opposite side of the signalterminals 325U and 325L, respectively.

On the module primary seal body 302 side, on the other hand, theelement-side DC positive connection terminal 315D, the element-side DCnegative connection terminal 319D, and the element-side AC connectionterminal 320D are formed on the conductor plates 315, 319, and 320,respectively. In addition, the element-side signal connection terminals327U and 327L are connected through a bonding wire 371 with the IGBTs328 and 330, respectively.

Next, the assembly process of the module primary seal body 302 will beexplained with reference to FIG. 17 to FIG. 21.

As shown in FIG. 17, the conductor plate 315 on the DC positiveelectrode side, the conductor plate 320 on the AC output side, and theelement-side signal connection terminals 327U and 327L are integrallyprocessed so that they are arranged on substantially the same plane in astate where they are tied to a common tie bar 372. The collectorelectrode of the IGBT 328 of the upper arm side and the cathodeelectrode of the diode 156 of the upper arm side are fixed to theconductor plate 315. The collector electrode of the IGBT 330 of thelower arm side and the cathode electrode of the diode 166 of the lowerarm side are fixed to the conductor plate 320. The conductor plate 318and the conductor plate 319 are arranged on substantially the same planeover the IGBTs 328 and 330 and the diodes 155 and 166. The emitterelectrode of the IGBT 328 of the upper arm side and the anode electrodeof the diode 156 of the upper arm side are fixed to the conductor plate318. The emitter electrode of the IGBT 330 of the lower arm side and theanode electrode of the diode 166 of the lower arm side are fixed to theconductor plate 319. Each of the power semiconductor elements is fixedthrough a metal bonding material 160 to an element fixing portion 322provided on each of the conductor plates. The metal bonding material 160is, for example, a soldering material, a silver sheet, a low-temperaturesintering jointing material including fine metallic particles, or thelike.

Each of the power semiconductor elements has a plate-like flatconfiguration, each of the electrodes of which is formed on the frontand back surfaces. As shown in FIG. 17, each of the electrodes of thepower semiconductor elements is sandwiched by the conductor plate 315and the conductor plate 318 or by the conductor plate 320 and theconductor plate 319. In other words, the conductor plate 315 and theconductor plate 318 are arranged in a layered manner opposite to eachother in substantially parallel through the IGBT 328 and the diode 156.Similarly, the conductor plate 320 and the conductor plate 319 arearranged in a layered manner opposite to each other in substantiallyparallel through the IGBT 330 and the diode 166. In addition, theconductor plate 320 and the conductor plate 318 are connected through anintermediate electrode 329. This connection causes the upper arm circuitand the lower arm circuit to be electrically connected, thereby formingan upper and lower arm series circuit.

As described above, the IGBT 328 and the diode 156 are sandwichedbetween the conductor plate 315 and the conductor plate 318, the IGBT330 and the diode 166 are sandwiched between the conductor plate 320 andthe conductor plate 319, and the conductor plate 320 and the conductorplate 318 are connected through the intermediate electrode 329 asillustrated in FIG. 18. After that, a control electrode 328A of the IGBT328 and the element-side signal connection terminal 327U are connectedthrough the bonding wire 371 and a control electrode 330A of the IGBT330 and the element-side signal connection terminal 327L are connectedthrough the bonding wire 371 as illustrated in FIG. 19.

Once the assembly has proceeded up to the state shown in FIG. 19, theportion including the power semiconductor elements and the bonding wire371 is sealed with the first sealing resin 348 as illustrated in FIG.20. At this time, the portion including the power semiconductor elementsand the bonding wire 371 is formed by mold-pressing from above and belowon the mold pressing surface 373 and filling the first sealing resin 348in the mold by transfer mold.

Upon sealing the portion including the power semiconductor elements andthe bonding wire 371 with the first sealing resin 348, the tie bar 372is removed so as to separate the element-side DC positive connectionterminal 315D, the element-side AC connection terminal 320D, and theelement-side signal connection terminals 327U and 327L individually.Then, each end of the element-side DC positive connection terminal 315D,the element-side DC negative connection terminal 319D, the element-sideAC connection terminal 320D, and the element-side signal connectionterminals 327U and 327L, which are aligned on one side of the moduleprimary seal body 302, is bent in the same direction as illustrated inFIG. 21. This will facilitate the work of metallically bonding themodule primary seal body 302 with the ancillary molded body 600 at theconnection section 370 and improve the productivity, thereby improvingthe reliability of the metal bond.

FIGS. 22A and 22B are views for explaining the transfer molding processof the first sealing resin 348. FIG. 22A shows a vertical sectional viewbefore clamping and FIG. 22B shows a vertical sectional view afterclamping.

As shown in FIG. 22A, the module primary seal body 302 before sealedshown in FIG. 19 is placed between an upper mold 374A and a lower mold374B. The upper mold 374A and the lower mold 374B sandwich and clamp themodule primary seal body 302 from above and below on the mold pressingsurface 373 so as to form a mold cavity 375 in the mold as shown in FIG.22B. The mold cavity 375 is filled with the first sealing resin 348 andformed so that the power semiconductor elements (the IGBTs 328 and 330and the diodes 155 and 166) are sealed with the first sealing resin 348in the module primary seal body 302.

It is to be noted that as shown in FIG. 20, on the mold pressing surface373, the element-side DC positive connection terminal 315D, theelement-side DC negative connection terminal 319D, the element-side ACconnection terminal 320D, the element-side signal connection terminal327U, and the element-side signal connection terminal 327L are aligned.Such terminal arrangement enables clamping using the upper mold 374A andthe lower mold 374B without generating unnecessary stress at theconnection section of each of the terminals with the power semiconductorelements and without a gap. Accordingly, the power semiconductorelements will be sealed without damaging the power semiconductorelements or leaking the first sealing resin 348 from the gap.

Next, the arrangement relationship between the control electrodes of thepower semiconductor elements and each of the terminals in the moduleprimary seal body 302 will be explained with reference to FIG. 23. FIG.23 shows a state where the conductor plates 318 and 319 and theintermediate electrode 329 are removed from the configuration in FIG. 18for better understanding. In FIG. 23, on one side of the IGBTs 328 and330 (upper side of the figure), the control electrodes 328A and 330A areeach arranged in a position shifted to the left in the figure withrespect to central lines 376 and 377, respectively. The central lines376 and 377 are perpendicular to the arrangement direction of theelement-side DC positive connection terminal 315D, the element-side DCnegative connection terminal 319D, the element-side AC connectionterminal 320D, the element-side signal connection terminal 327U, and theelement-side signal connection terminal 327L.

Dividing the IGBT 328 by the central line 376, the element-side signalconnection terminal 327U is arranged on the half side in which thecontrol electrode 328A is arranged and the element-side DC positiveconnection terminal 315D is arranged on the other half side. Similarly,dividing the IGBT 330 by the central line 377, the element-side signalconnection terminal 327L is arranged on the half side in which thecontrol electrode 330A is arranged and the element-side AC connectionterminal 320D is arranged on the other half side. In addition, as shownin FIG. 18, the element-side DC negative connection terminal 319D isarranged between the element-side DC positive connection terminal 315Dand the element-side signal connection terminal 327L. Such arrangementminimizes the length of the bonding wire 371, which connects the controlelectrodes 328A and 330A with the element-side signal connectionterminals 327U and 327L, respectively, thereby improving the reliabilityin connection. In addition, collective arrangement of each of theterminals will achieve reduction in size of the module primary seal body302 and thus the power module 300U.

It is to be noted that as shown in FIG. 23, the element-side DC positiveconnection terminal 315D, the element-side AC connection terminal 320D,the element-side signal connection terminal 327U, and the element-sidesignal connection terminal 327L are integrally processed in a statewhere they are tied to the common tie bar 372. This will significantlyreduce variations in flatness and thickness among these terminals. Onthe other hand, since the element-side DC negative connection terminal319D is combined with that having been processed separately from each ofthe above terminals, variations in flatness and thickness become greaterthan each of the other terminals, and thus unnecessary stress may occurat the connection section of the terminal and the power semiconductorelements when clamping.

FIG. 24 is a view showing a variation for avoiding the disadvantagedescribed above. In this variation, a stress relief section 319E forabsorbing and relieving the stress when clamping is provided on theconductor plate 319 on which the element-side DC negative connectionterminal 319D is provided. The stress relief section 319E is preferredto be positioned between the area on which the power semiconductorelements are mounted (soldered area) and the mold pressing surface 373.It is to be noted that it may be conceived that the stress reliefsection 319E is prepared by simply making the conductor plate 319 partlythinner than other portions. In that case, however, the current densityincreases at the thin portion, which may reduce electrical performance.Hence, as shown in FIG. 24, it is preferred that a part of the conductorplate 319 is bent to provide the stress relief section 319E. Thisprevents the current density from increasing at the stress reliefsection 319E and the current flows in opposite directions at the turningportion, provided by bending, thereby also contributing to reduction ofinductance.

FIG. 25 is a circuit diagram showing the circuit configuration of thepower module 300U. The collector electrode of the IGBT 328 of the upperarm side and the cathode electrode of the diode 156 of the upper armside are connected through the conductor plate 315. Similarly, thecollector electrode of the IGBT 330 of the lower arm side and thecathode electrode of the diode 166 of the lower arm side are connectedthrough the conductor plate 320. In addition, the emitter electrode ofthe IGBT 328 of the upper arm side and the anode electrode of the diode156 of the upper arm side are connected through the conductor plate 318.Similarly, the emitter electrode of the IGBT 330 of the lower arm sideand the anode electrode of the diode 166 of the lower arm side areconnected through the conductor plate 319. The conductor plates 318 and320 are connected through the intermediate electrode 329. Such circuitconfiguration forms the upper and lower arm series circuit.

Next, an effect produced by the reduction of inductance will beexplained with reference to FIGS. 26A and 26B. FIG. 26A is a diagramshowing an equivalent circuit when a recovery current flows through andFIG. 26B is a view showing the recovery current path.

In FIG. 26A, the diode 166 of the lower arm side is assumed to be madeconductive in a forward bias state. In this state, when the IGBT 328 ofthe upper arm side enters an ON state, the diode 166 of the lower armside is reverse-biased and recovery current due to carrier mobilitypasses through the upper and lower arms. At this time, a recoverycurrent 360 flows through each of the conductor plates 315, 318, 319,and 320 as shown in FIG. 26B. The recovery current 360 passes throughthe DC positive terminal 315B (157), which is arranged opposite to theDC negative terminal 319B (158), as indicated by the dotted line, thenflows through a loop-shaped path formed by each of the conductor plates315, 318, 319, and 320, and flows through the DC negative terminal 319B(158), which is arranged opposite to the DC positive terminal 315B(157), again as indicated by the solid line. The flow of current throughthe loop-shaped path causes an eddy current 361 to flow through thefirst heat dissipation surface 307A and the second heat dissipationsurface 307B of the module case 304. The magnetic field canceling effectproduced by an equivalent circuit 362 in the current path of the eddycurrent 361 reduces a wiring inductance 363 in the loop-shaped path.

It is to be noted that the inductance reduction effect increases as thecurrent path of the recovery current 360 is closer to a loop shape. Inthe present embodiment, as indicated by dotted line, the loop-shapedcurrent path goes through a path close to the DC positive terminal 315B(157) side of the conductor plate 315 and passes through the IGBT 328and the diode 156. Then, as indicated by the solid line, the loop-shapedcurrent path goes through a path farther than the DC positive terminal315B (157) side of the conductor plate 318, and then, as indicated bythe dotted line, goes through a path farther than the DC positiveterminal 315B (157) side of the conductor plate 320 and passes throughthe IGBT 330 and the diode 166. In addition, as indicated by the solidline, the loop-shaped current path goes through a path close to the DCnegative wiring 319A side of the conductor plate 319. The loop-shapedcurrent path thus goes through paths of a closer side or a farther sidewith respect to the DC positive terminal 315B (157) and the DC negativeterminal 319B (158) so as to form a current path closer to a loop shape.

FIG. 38 is a view showing a variation with a divided DC negative wiring.It is to be noted that structures denoted by the same reference numeralas that described earlier have the same function. Since the element-sideDC negative connection terminal 319D shown in FIG. 18 is combined withthat having been processed separately from each of the above terminals,variations in flatness and thickness become greater than each of theother terminals, and thus unnecessary stress may occur at the connectionsection of the terminal and the power semiconductor elements whenclamping.

Then, as shown in FIG. 38, the element-side DC negative connectionterminal 319D shown in FIG. 18 is divided so that a negativeelectrode-side connection terminal 319F is arranged on substantially thesame plane as the element-side AC connection terminal 320D and theelement-side DC positive connection terminal 315D.

In addition, as shown in FIG. 39, an element-side DC negative connectionterminal 319G extends from an edge of the conductor 319 to a positionopposite to a part of the negative electrode-side connection terminal319F. Then, the end of the element-side DC negative connection terminal319G is bent towards the negative electrode-side connection terminal319F side.

Then, as shown in FIG. 40, the end of the element-side DC negativeconnection terminal 319G is connected with the negative electrode-sideconnection terminal 319F through a metal bonding material 161. After thevariety of semiconductor elements and terminals are bonded with themetal bonding material, the module body shown in FIG. 40 is sealed withthe first sealing resin 348 according to the production method shown inFIGS. 22A and 22B, and thus a module primary seal body is completed asshown in FIG. 41. As shown in FIG. 41, the negative electrode-sideconnection terminal 319F is formed integrally with the tie bar 372together with the element-side DC positive connection terminal 315D, theelement-side AC connection terminal 320D, and the element-side signalconnection terminal 327U. It is then possible to cut the tie bar 372collectively with the connection section with the negativeelectrode-side connection terminal 319F.

This will significantly reduce variations in flatness and thicknessamong these terminals.

FIG. 27 is an external perspective view of the capacitor module 500. Aplurality of capacitor cells are provided in the capacitor module 500.On the upper surface of the capacitor module 500, capacitor terminals503 a to 503 c are provided in a protruding manner adjacent to theopposite surface to the flow path 19 of the capacitor module 500. Thecapacitor terminals 503 a to 503 c are formed corresponding to thepositive terminal 157 and the negative terminal 158 of each of the powermodules 300. The capacitor terminals 503 a to 503 c are provided in thesame shape and an insulation sheet is provided between the negativeelectrode-side capacitor terminal 504 and the positive electrode-sidecapacitor terminal 506, which constitute the capacitor terminals 503 ato 503 c, thereby ensuring insulation between the terminals.

Protruding portions 500 e and 500 f are formed above a lateral surface500 d side of the capacitor module 500. A discharge resistor is mountedin the protruding portion 500 e and a Y capacitor for protecting againstcommon-mode noise is mounted in the protruding portion 500 f. Inaddition, the power supply terminal 508 and 509 shown in FIG. 5 aremounted to terminals 500 g and 500 h protruding from the upper surfaceof the protruding portion 500 f. As shown in FIG. 10, recesses 405 a and405 b are formed between the openings 402 b and 402 c and the lateralsurface 12 d, so that, when the capacitor module 500 is housed in thehousing space 405 of the flow path former 12, the protruding portion 500e is housed in the recess 405 a and the protruding portion 500 f ishoused in the recess 405 b.

The discharge resistor mounted in the protruding portion 500 e is aresistor for discharging electric charge accumulated at the capacitorcells in the capacitor module 500 when the inverter is stopped. Therecess 405 a in which the protruding portion 500 e is housed is provideddirectly above the flow path of cooling water flowing in from the inletpipe 13, thereby inhibiting rise in temperature at the dischargeresistor when discharging.

FIG. 28 is a perspective view of the bus bar assembly 800. The bus barassembly 800 includes the AC bus bars 802U, 802V, and 802W of the U, V,and W phases, a holding member 803 for holding and fixing the AC busbars 802U to 802W, and the current sensor module 180 for detecting ACcurrent flowing through the AC bus bars 802U to 802W. The AC bus bars802U to 802W are each formed of a wide conductor. On the holding member803, formed of insulation material such as resin, the plurality ofsupporting members 807 a for holding the driver circuit board 22 areformed in a protruding manner upward from the holding member 803.

The current sensor module 180 is arranged on the bus bar assembly 800 sothat the current sensor module 180 is in parallel to the lateral surface12 d at a position adjacent to the lateral surface 12 d of the flow pathformer 12 when the bus bar assembly 800 is fixed on the flow path former12 as shown in FIG. 8 described earlier. As shown in FIG. 28, throughholes 181 through which the AC bus bars 802U to 802W pass are formed ona lateral surface of the current sensor module 180. Sensor elements areprovided in portions where the through holes 181 of the current sensormodule 180 are formed, and signal lines 182 a of each of the sensorelements protrude from the upper surface of the current sensor module180. Each of the sensor elements are aligned in the extending directionof the current sensor module 180, i.e., the extending direction of thelateral surface 12 d of the flow path former 12. The AC bus bars 802U to802W passes through the corresponding through hole 181 and their endportion protrude in parallel.

Protrusions 806 a and 806 b for positioning are formed on the holdingmember 803 in an upward protruding manner. The current sensor module 180is screwed to the holding member 803, where the current sensor module180 is positioned by engaging the protrusions 806 a and 806 b withpositioning holes formed in the frame body of the current sensor module180. In addition, when fixing the driver circuit board 22 to thesupporting members 807 a, the protrusions 806 a and 806 b forpositioning are engaged into the positioning holes formed on the drivercircuit board 22 side, so that the signal line 182 a of the currentsensor module 180 is positioned into the through hole of the drivercircuit board 22. The signal line 182 a is soldered to the wiringpattern of the driver circuit board 22.

In the present embodiment, the holding member 803, the supportingmembers 807 a and the protrusions 806 a and 806 b are integrallyprovided with resin. Since the holding member 803 thus has a positioningfunction of the current sensor module 180 and the driver circuit board22, assembling and soldering works between the signal line 182 a and thedriver circuit board 22 are made easy. In addition, a mechanism to holdthe current sensor module 180 and the driver circuit board 22 isprovided on the holding member 803, thereby reducing the number ofcomponents in the power conversion device as a whole.

The AC bus bars 802U to 802W are fixed to the holding member 803 so thattheir wide surfaces are leveled out and connection sections 805 to beconnected to the AC terminals 159 of the power modules 300U to 300W areerected vertically. The connection sections 805 each have a protrudingand recessed end, on which heat concentrates upon welding.

Since the current sensor module 180 is arranged in parallel to thelateral surface 12 d of the flow path former 12 as described above, eachof the AC bus bars 802U to 802W protruding from the through hole 181 ofthe current sensor module 180 is to be arranged on the lateral surface12 d of the flow path former 12. Since each of the power modules 300U to300W is arranged on the flow path section 19 a, 19 b, and 19 c formedalong the lateral surfaces 12 a, 12 b, and 12 c of the flow path former12, the connection sections 805 of the AC bus bars 802U to 802W arearranged at positions corresponding to the lateral surface 12 a to 12 cof the bus bar assembly 800. As a result, as shown in FIG. 8, the Uphase AC bus bar 802U extends from the power module 300U arranged in thevicinity of the lateral surface 12 b to the lateral surface 12 d, the Vphase AC bus bar 802V extends from the power module 300V arranged in thevicinity of the lateral surface 12 a to the lateral surface 12 d, andthe W phase AC bus bar 802W extends from the power module 300W arrangedin the vicinity of the lateral surface 12 c to the lateral surface 12 d.

FIG. 29 is a view showing the flow path former 12 in which the powermodules 300U to 300W are fixed in the openings 402 a to 402 c and thecapacitor module 500 is housed the housing space 405. In the exampleshown in FIG. 29, the power module 300U of the U phase is fixed in theopening 402 b, the power module 300V of the V phase is fixed in theopening 402 a, and the power module 300W of the W phase is fixed in theopening 402 c. After that, the capacitor module 500 is housed in thehousing space 405 and the terminal on the capacitor side and theterminal of each of the power modules are connected by welding or thelike. Each of the terminals protrudes from the upper end surface of theflow path former 12, and welding work is carried out by bringing thewelding machine from above.

It is to be noted that the positive and negative terminals 157 and 158of each of the power modules 300U to 300W provided in a U shape areconnected with the capacitor terminals 503 a to 503 c provided in aprotruding manner on the upper surface of the capacitor module 500.Since the three power modules 300U to 300W are provided to surround thecapacitor module 500, the positional relationship of each of the powermodules 300U to 300W with respect to the capacitor module 500 becomesequivalent, each of the power modules 300U to 300W will thus beconnected to the capacitor module 500 in a well-balanced manner usingthe capacitor terminals 503 a to 503 c having the same shape. Due tothis, the circuit constant of the capacitor module 500 and the powermodules 300U to 300W becomes easily balanced in each of the threephases, thereby achieving a configuration in which current is easilyinput and output.

FIG. 30 is a horizontal sectional view of the flow path former 12 inwhich the power modules 300U to 300W and the capacitor module 500 arearranged as shown in FIG. 29. As described above, the U shaped flow path19 is formed in the flow path former 12, and the U phase power module300U is arranged at the flow path section 19 b formed along the lateralsurface 12 b on the left side of the figure. Similarly, the V phasepower module 300V is arranged at the flow path section 19 a formed alongthe lateral surface 12 a on the opposite side of the lateral surface 12d on which the pipes 13 and 14 are provided, and the W phase powermodule 300W is arranged at the flow path section 19 c formed along thelateral surface 12 on the right side.

Openings 12 g and 12 h are formed on the lateral surface 12 d of theflow path former 12. The opening 12 g communicates with the flow pathsection 19 b through a communication path 12 e. The opening 12 hcommunicates with the flow path section 19 c through a communicationpath 12 f. The pipes 13 and 14 arranged in the openings 12 g and 12 hare mounted to the communication paths 12 e and 12 f in a press fittingmanner.

FIG. 37 shows a sectional view of the flow path former 12 seen from thearrow direction of the A-A cross section of FIG. 30. It is to be notedthat FIG. 37 shows a state in which the A-A cross section ishorizontally inverted. The communication path 12 e significantly changesin the shape of the flow path cross section along the flow direction ofcooling water. In addition, the flow of cooling water of the presentembodiment is bifurcated by the lateral surface of the power module300U, so that one of the bifurcated flows heads for the first heatdissipation surface 307A side of the module case 304 and the other headsfor the second heat dissipation surface 307B side of the module case304. It is to be noted that the first heat dissipation surface 307A, notillustrated in FIG. 37, is a heat dissipation surface on the other sideof the second heat dissipation surface 307B shown in FIG. 37. Therefore,hit of the flow of cooling water of the present embodiment against thelateral surface of the power module 300U tends to increase pressure lossfor causing the cooling water to flow. In order to inhibit such increasein the pressure loss, it is necessary to regulate the flow of coolingwater in the vicinity of the lateral surface portion of the power module300U. Thus, an entrance section 12 j is formed in the direction from theinlet pipe 13 side towards the power module 300U with its width in theheight direction increasing in a stepwise manner. It is to be noted thatthe entrance section 12 j may not be provided in the stepwise manner asin FIG. 37 but may be provided in a smooth slope-like shape.

In the present embodiment, the U shaped flow path 19 is formed along thethree lateral surfaces 12 a to 12 c of the flow path former 12 having asubstantially square planar shape and the power modules 300U to 300W arearranged at the flow path sections 19 a to 19 c so that the powermodules 300U to 300W, each of which has a flat shape, are in parallelwith the lateral surfaces 12 a to 12 c. Then, the capacitor module 500,which is an electric component, is housed in the center space (thehousing space 405) surrounded by the flow path 19. Such modulearrangement allows the flow path former 12, in which the power modules300U to 300W and the capacitor module 500 are housed, to be reduced insize.

It is to be noted that, when the three power modules 300U to 300W arearranged into a U shape, as shown in FIG. 30, at least a part of thepower module 300V to be arranged between the pair of power modules 300Uand 300W arranged in parallel is arranged to fit into a space sandwichedby the power modules 300U and 300W, thereby further reducing the size.

FIG. 31 is a schematic view for explaining the arrangement of the threepower modules 300U to 300W. It is to be noted that the power modules300U to 300W have the same configuration and the same shape. The widthof the lateral surfaces 12 b and 12 c of the flow path former needs tobe at least around the sum of a length L1 along the flow path of thepower modules 300U to 300W and a length L2 of the communication path. Onthe other hand, the lateral surface 12 a requires at least around thelength L1. It is naturally conceivable that in practice, as shown inFIG. 30, the dimension needs to be slightly adjusted in view of the flowof cooling water e.g., the connection section of the flow path section.

For this reason, in order to minimize the footprint of the powerconversion device 20, the shape seen with a planar view (planar shape)is provided in a substantially square so as to reduce the powerconversion device 200 in size. Since the communication path is necessarywith respect to the direction along the lateral surfaces 12 b and 12 cas described above, from a point of view of reduction in size it ispreferred to arrange the power module 300V so that a part of the powermodule 300V is included in a space S1 between the pair of the powermodules 300U and 300W as shown in FIG. 31.

The lateral dimension (the width dimension of the lateral surface 12 a)of the arrangement space in FIG. 31 is at least around L1+2·L3 where thethickness of the power module is denoted by L3. Then, L3 and L4 are setso that the longitudinal dimension L1+L2+(L3−L4) is comparable toL1+2·L3, thereby reducing the area in the planar view and making itsubstantially square. At this time, the flow path section 19 a is formedso as to pass through the space between the power modules 300U and 300Was shown in FIG. 30. It is to be noted that in the example shown in FIG.30, due to limitation in the dimensions of the capacitor module 500, theinterval between the power modules 300U and 300W is slightly larger thanthe length L1 of the power module 300V.

The space above the pipes 13 and 14 and the hole 12 e and the hole 12 fthrough which the pipes 13 and 14 are to be press-fitted will be anempty space. Then, the recesses 405 a and 405 b are formed in this spaceas shown in FIG. 10 and the protruding portion 500 e, which is adischarge resistor mounting portion of the capacitor module 500, and theprotruding portion 500 f, which is a Y capacitor mounting portion, arearranged as shown in FIG. 29 so that the empty space is effectivelyutilized, thereby contributing to reduction in size of the powerconversion device 200. The pipes 13 and 14 are collectively positionedon the single lateral surface 12 d so that the flow of cooling water isstraighten from the inlet pipe 13 to the flow path section 19 b and fromthe flow path section 19 c to the outlet pipe 14, thereby reducingpressure loss significantly. In addition, an increase in installationspace of the device due to the protrusion of the pipes will beprevented, thereby improving the in-vehicle mountability. In addition,the pipes 13 and 14 are press-fitted to the holes 12 e and 12 f only onone surface of the housing, thereby improving the workability andproductivity.

In addition, the flow path 19 is provided to surround the three sides ofthe capacitor module 500, thereby cooling the capacitor module 500effectively. Incidentally, since the power conversion device 200 of thepresent embodiment is to be mounted on a vehicle, it is often arrangedin an engine bay in general. Since inside the engine bay becomesrelatively high in temperature due to heat from the engine, the travelmotor, and the like, heat penetration from the surrounding to the powerconversion device 200 becomes an issue. However, as shown in FIG. 30,the capacitor module 500 is surrounded on its three sides by the flowpath 19 through which the cooling water flows, thereby effectivelyblocking the heat penetration from the surrounding of the device.

After the power modules 300U to 300W and the capacitor module 500 arearranged in the flow path former 12 as shown in FIG. 29, the bus barassembly 800 is fixed above the capacitor module 500 as shown in FIG. 8and welding work of the terminals is carried out. In the presentembodiment, the bus bars 802U to 802W connected to the terminals of thepower modules 300U to 300W arranged in a U shape are wired above thecapacitor module 500 away from each of the connection sections and drawnfrom the lateral surface 12 d side of the flow path former 12. As aresult, without spanning over the power module and with ensuringsufficient insulation properties, the bus bars 802U to 802W will becollectively arranged in one position, i.e., the space of the opening 10a of the housing 10 to which the AC interface 185 is mounted (refer toFIG. 5).

Such bus bar configuration will keep the power modules 300U to 300W awayfrom the AC connector section where heat is generated and temperature islikely to rise, thereby inhibiting the heat from being transmitted tothe power modules 300U to 300W through the bus bars 802U to 802W. Inaddition, the bus bars 802U to 802W are arranged other than above theflow path 19, thereby reducing the possibility of electrical leakagecaused by water leak even if the water leaks from the flow path 19.

In addition, the bus bar assembly 800 is configured to be fixed to theflow path former 12 through which cooling water flows, thereby not onlyinhibiting the rise in temperature of the bus bar assembly 800 but alsoinhibiting the rise in temperature of the current sensor 180 held in thebus bar assembly 800. The sensor element provided in the current sensor180 has a heat-sensitive feature and thus the above configuration willimprove the reliability of the current sensor 180.

After the terminals are welded by fixing the bus bar assembly 800 to theflow path former 12 as shown in FIG. 8, the driver circuit board 22 isfixed to the supporting members 807 a, formed on the holding member 803of the bus bar assembly 800, as shown in FIG. 6. The vehicle-mountedpower conversion device 200 is susceptible to an effect of vibrationsfrom the vehicle. Hence, the plurality of supporting members 807 aformed in the holding member 803 are configured to support the drivercircuit board 22 not only in the periphery thereof but also in thevicinity of the center, thereby reducing the effect of vibrationsapplied to the driver circuit board 22.

For instance, the supporting members 807 a supports the driver circuitboard 22 in the center so that the resonance frequency of the drivercircuit board 22 will be made higher than the frequency of vibrationstransmitted from the vehicle side, thereby reducing the effect ofvibrations to the driver circuit board 22. It is to be noted that thedriver circuit board 22 is screwed to the supporting members 807 a.

After the driver circuit board 22 is fixed above the bus bar assembly800, the housing 10 is bolted to the flow path former 12 as shown inFIG. 6 and the control circuit board 20 is fixed on the dividing wall 10c which sections between the upper housing space and the lower housingspace of the housing 10. The driver circuit board 22 in the lowerhousing space and the control circuit board 20 in the upper housingspace are connected through the flat cable as shown in FIG. 7. Asdescribed above, the dividing wall 10 c is provided with the slit-likeopening 10 d for drawing the flat cable from the lower housing space tothe upper housing space.

Since the power modules 300U to 300W are arranged in a U shape along thethree lateral surfaces 12 b, 12 a, and 12 c of the flow path former 12,control terminals from each of the power modules 300U to 300W to beconnected to the driver circuit board 22 are also aligned in a U shapealong the sides of the driver circuit board 22 corresponding to thelateral surfaces 12 b, 12 a, and 12 c as shown in FIG. 6. A controlsignal for driving and controlling the power modules 300U to 300W is ofhigh voltage. On the other hand, a sensor signal of the current sensor180 and a signal by the flat cable are of low voltage. It is thuspreferred that the wiring of the high-voltage system and the wiring ofthe low-voltage system are arranged away from each other in order toreduce the effect of noise of the high-voltage system against thelow-voltage system.

In the present embodiment, since the power modules 300U to 300W arearranged in a U shape along the lateral surfaces 12 b, 12 a, and 12 c,the space in the vicinity of the side corresponding to the lateralsurface 12 d on the driver circuit board 22 will be utilized as a spaceaway from the control terminal. In the present embodiment, since the busbars 802U to 802W, which are the targets of detection by the currentsensor 180, are collectively arranged on the lateral surface 12 d side,the current sensor 180 is arranged in parallel in the vicinity of thelateral surface 12 d. Due to this, the signal terminal 182 a is arrangedin a space in the vicinity of the side corresponding to the lateralsurface 12 d on the driver circuit board 22 described above, and will besufficiently kept away from the control terminal of the high-voltagesystem. It is to be noted that in the driver circuit board 22, the flatcable is arranged on the side of the driver circuit board 22corresponding to the lateral surface 12 c and connected on the board inthe vicinity of the lateral surface 12 d away from the control terminalso as to reduce the effect from the control terminal. This allows thepattern for low-voltage signals and the pattern for high-voltage signalsto be separated easily on the driver circuit board 22.

In addition, the control circuit board 20 of the low-voltage system isarranged in the upper housing space separated by the dividing wall 10 cand the flat cable is drawn from the lower housing space through theslit-like opening 10 d, thereby reducing the effect of noise on thecontrol circuit board 20. Thus, noise is sufficiently protected in thepower conversion device 200 of the present embodiment.

In addition, the power conversion device 200 of the present embodimenthas a configuration in which the capacitor module 500 and the powermodules 300U to 300W are arranged on the flow path former 12 so that thework of fixing the necessary components such as the bus bar assembly 800and the board can be carried out in order from the bottom, therebyimproving the productivity and reliability.

FIG. 32 is a view showing a cross section of the power conversion device200, the sectional view in which the power conversion device 200 is seenfrom the direction of the pipes 13 and 14. The openings 402 a to 402 c,formed on the flow path former 12, are covered with the flange 304 b,provided in the module case 304 of the power modules 300U to 300W. It isto be noted that although not shown in the figure, a sealing material isprovided between the flange 304 b and the flow path former 12 so as toensure air tightness. In the power modules 300U to 300W, a heatdissipation surface space in which the fins 305 for heat dissipation areprovided is arranged in the flow path 19 and the lower end portion inwhich the fins 305 are not provided is housed inside an inner recess ofthe raised portion 406 formed on the lower cover 420. This will preventcooling water from flowing into a space in which the fins 305 are notformed. In the power conversion device 200 of the present embodiment,since the capacitor module 500 which is relatively heavy in weight isarranged in the lower center of the power conversion device 200 as shownin FIG. 32, the power conversion device 200 has a good balance of thecenter of gravity, thereby keeping the power conversion device 200 frommoving even if vibrations are applied.

FIG. 33 is a view explaining an arrangement of the power conversiondevice 200 of the present embodiment when mounted to a vehicle. FIG. 33shows the arrangement in an engine bay 1000 in terms of three layoutpatterns A to C in the same figure. The lower side of the figurecorresponds to the vehicle front, and a radiator 1001 is arranged on thefront side of the engine bay 1000. The transmission TM with the built-inmotor generator MG1 is arranged on the rear side of the radiator 1001.In addition, the connector 21 for signals is connected to a vehiclesignal harness provided in the engine bay 1000. It is to be noted thatwhile the battery 136 is not illustrated in FIG. 33, the battery 136 isheavy in weight and therefore it is arranged in the vicinity of thecenter of the vehicle, i.e., rearward of the vehicle from the engine bay1000 in general.

Connection between the power conversion device 200 and the vehicle sideis related to the arrangement of the pipes 13 and 14 relating to thecooling water, the AC connector 187 for supplying AC power to the motorgenerator MG1, and the connector 21 for communication to be connected tothe higher-order control circuit provided on the vehicle side. In thepresent embodiment, the AC connector 187 and the pipes 13 and 14 arearranged on the lateral surface 12 d side of the flow path former 12,the connector 21 for signals is arranged on the lateral surface 12 b,and the DC connector 138 is arranged on the lateral surface 12 c. Inaddition, the AC wiring 187 a drawn from the AC connector 187 is drawnto the lower side of the power conversion device 200 through between thepipes 13 and 14. Similarly, the DC wiring 138 a of the DC connector 138is also drawn to the lower side of the power conversion device 200.

In each of the layout patterns A to C of FIG. 33, the power conversiondevice 200 is arranged above the transmission TM. In addition, thecooling water of the radiator 1001 is supplied to the flow path 19 ofthe flow path former 12. For this reason, in view of the workability ofthe cooling pipes and the AC wiring 187 a, it is preferred to arrangethe power conversion device 200 so that the lateral surface 12 d onwhich the pipes 13 and 14 and the AC connector 187 are provided isarranged towards the direction of the radiator 1001 or the transmissionTM. In addition, since the battery 136, which is a DC power supply, isprovided rearward from the engine bay 1000, it is preferred that thelateral surface 12 c, on which the DC connector 138 is mounted, isarranged towards the rear in view of wiring of the DC wiring 138 a.

There are the three possible layout patterns A to C shown in FIG. 33 toarrange the power conversion device 200 inside the engine bay 1000. Inview of the connection relationship among the radiator 1001, the battery136, and the transmission TM described above, it is preferred in thelayout pattern A that the lateral surface 12 d is arranged towards thedirection of the transmission TM and in the layout patterns B and C thatthe lateral surface 12 d is arranged towards the direction of theradiator 1001.

In the layout pattern A, the DC connector 138, the AC connector 187, andthe connector 21 for signals face in a preferred direction in terms ofthe wiring layout. In addition, since the pipes 13 and 14 face in thedirection of the transmission TM, the cooling pipes are required to bebent in the direction of the radiator 1001. However, since the AC wiring187 a is drawn downward from the AC connector 187, interference betweenthe cooling pipes and the AC wiring 187 a will be avoided and reductionin workability will be prevented.

In the layout pattern B, the pipes 13 and 14, the AC connector 187, andthe connector 21 for signals face in a preferred direction. In addition,although the DC connector 138 faces towards the side of the vehicle,reduction in workability is avoided because the DC wiring 138 a drawndownward from the DC connector 138 may simply be wired rearwards.

In the layout pattern C, giving priority to the layout of the coolingpipes, the lateral surface 12 d is arranged towards the direction of theradiator 1001. In this case, although the AC wiring 187 a is to be wiredin the direction of the transmission TM, the AC wiring 187 a and coolingpipe will not interfere because the AC wiring 187 a is drawn downwardthrough between the pipes 13 and 14. Therefore, no trouble will occur inthe piping work and the wiring work.

Thus, in the power conversion device 200 of the present embodiment, thepipes 13 and 14, the DC connector 138, the AC connector 187, and theconnector 21 for signals are arranged in the engine bay 1000 in apreferred manner. As a result, a variety of situations as in the layoutpatterns A to C are managed, thereby providing the power conversiondevice 200 with excellent in-vehicle mountability.

It is to be noted that in the embodiment described above, the powermodules 300U to 300W have a structure in which the unit in which thepower semiconductor elements are sandwiched by the conductor plates ishoused in the module case 304, on both the front and back surfaces ofwhich the heat dissipation surfaces on which the fins 305 are formed areprovided. Thus, the power modules 300U to 300W are provided in the flowpath 19 in the center of the flow path. However, the arrangement methodof the power module is not limited to that described above and a varietyof arrangements are possible.

The examples shown in FIG. 34 and FIG. 35 show an arrangement method ofthe power module in which only one surface of the module caseconstitutes a heat dissipation surface. The power modules 301U to 301W,which correspond to the power modules 300U to 300W described above, areprovided with the fins 305 for heat dissipation only on one surface ofthe flat power module.

In the case of FIG. 34, the power modules 301U to 301W are arranged tobe closely attached to the inner peripheral surfaces of the flow pathsections 19 a to 19 c, i.e., the wall surfaces surrounding the capacitormodule 500. Cooling water flows along the heat dissipation surfaces onwhich the fins 305 are formed. In the example shown in FIG. 35, on thecontrary to the case of FIG. 34, the power modules 301U to 301W arearranged to be closely attached to the outer peripheral surfaces of theflow path sections 19 a to 19 c.

It is to be noted that while in FIGS. 34 and 35, the whole power modules301U to 301W are arranged in the flow path 19, they may be arranged sothat only the heat dissipation surfaces are exposed in the flow path 19as in FIG. 36. While in the example shown in FIG. 36, the powersemiconductor elements are provided on a heat sink 3010, on the backside of which the fins 305 are formed, they will be arranged in the samemanner in a configuration covered with the casing as shown in FIGS. 34and 35.

The following operations and advantageous effects can be achievedaccording to the present embodiment explained above.

(1) The power module 300U includes the IGBTs 328 and 330 and the diodes156 and 166, being power semiconductor elements constituting the upperand lower arms of the inverter circuit 140, the first sealing resin 348,having a polyhedron shape and seals the IGBTs 328 and 330 and the diodes156 and 166, the positive electrode-side terminal (the DC positivewiring 315A and the element-side DC positive connection terminal 315D)and the negative electrode-side terminal (the DC negative wiring 319Aand the element-side DC negative connection terminal 319D), beingconnected with any of these power semiconductor elements and eachprotrude from the first sealing resin 348, the second sealing resin 351,sealing at least a part of those terminals, and the module case 304, inwhich the IGBTs 328 and 330 and the diodes 156 and 166 having beensealed with the first sealing resin 348 are housed. The power module300U is configured so that the positive electrode-side terminal and thenegative electrode-side terminal are aligned at their portionsprotruding from the first sealing resin 348, along one surface of thefirst sealing resin 348, protrude in a layered state from the secondsealing resin 351, and extend out of the module case 304. This willprevent over stress on the connection sections of the powersemiconductor elements with the positive electrode-side terminal and thenegative electrode-side terminal and a gap in the mold from occurring atthe time of clamping performed when the power semiconductor elements aresealed with the first sealing resin 348.

(2) The power module 300U includes the series circuit 150 of the IGBTs328 and 330 and the diodes 156 and 166 for the upper arm and the lowerarm of the inverter circuit 140, the first sealing resin 348, sealingthe series circuit 150, the element-side DC positive connection terminal315D and the element-side DC negative connection terminal 319D,protruding from the first sealing resin 348 and supplying DC power tothe series circuit 150, the DC positive wiring 315A (the DC positiveterminal 315B and the ancillary module-side DC positive connectionterminal 315C) and the DC negative wiring 319A (the DC negative terminal319B and the ancillary module-side DC negative connection terminal 319C)with a layer structure connected to the element-side DC positiveconnection terminal 315D and the element-side DC negative connectionterminal 319D, the second sealing resin 351, sealing those connectionsections 370, and the module case 304 in which the series circuit 150sealed with the first sealing resin 348 and the element-side DC positiveconnection terminal 315D and the element-side DC negative connectionterminal 319D are housed. The power module 300U is provided with aconfiguration with the DC positive wiring 315A and the DC negativewiring 319A extending out of the module case 304, and magnetic fluxesare to be generated in directions canceling each other out by currentsflowing through the DC positive wiring 315A and the DC negative wiring319A of each layer. This will achieve reduction of inductance.

(3) The module case 304 is formed of an electrically conductive member,and the eddy current 361 is to be induced in the module case 304 by therecovery current 360 flowing through the series circuit 150 connected tothe element-side DC positive connection terminal 315D and theelement-side DC negative connection terminal 319D. This will reduce thewiring inductance 363 in the loop-shaped path when the recovery current360 is flowing.

(4) The module case 304 is provided with the first heat dissipationsurface 307A and the second heat dissipation surface 307B which includethe fins 305 for heat dissipation outside thereof. Inside the modulecase 304, the IGBTs 328 and 330 and the diodes 156 and 166, constitutingthe series circuit 150 sealed with the first sealing resin 348, arearranged opposite to the first heat dissipation surface 307A and thesecond heat dissipation surface 307B. This allows heat to be dissipatedeffectively from the IGBTs 328 and 330 and the diodes 156 and 166.

(5) The power module 300U further includes the element-side signalconnection terminals 327U and 327L, transmitting drive signals of theIGBTs 328 and 330 output from the driver circuit 174, and the signalwirings 324U and 324L, being connected with the element-side signalconnection terminals 327U and 327L by metallic bonding. In the powermodule 300U, the second sealing resin 351 further seals the connectionsections 370 between the element-side signal connection terminals 327Uand 327L and the signal wirings 324U and 324L. Since in this manner, theconnection sections 370 of each of the wirings and the terminals are tobe collectively sealed, the manufacturing process is simplified, therebyimproving the productivity.

(6) The element-side signal connection terminals 327U and 327L, theelement-side DC positive connection terminal 315D, and the element-sideDC negative connection terminal 319D each protrude in the same directionfrom the first sealing resin 348, each of their ends is bent in the samedirection. Each of the ends, having been thus bent, is to bemetallically bonded with the signal wirings 324U and 324L or the DCpositive wiring 315A and the DC negative wiring 319A. This willfacilitate the work of metal bonding and improve the productivity,thereby improving the reliability of the metal bond.

(7) The element-side signal connection terminals 327U and 327L and theelement-side DC positive connection terminal 315D and the element-sideDC negative connection terminal 319D are to be aligned at their portionsprotruding from the first sealing resin 348. This will facilitate thefirst sealing resin 348 in sealing.

(8) The power module 300U further includes the element-side ACconnection terminal 320D, protruding from the first sealing resin 348,for outputting AC power having been converted from DC power by theseries circuit 150 and the AC wiring 320A (the AC terminal 320B and theancillary module-side AC connection terminal 320C) to be connected withthe element-side AC connection terminal 320D by metallic bonding. In thepower module 300U, the second sealing resin 351 further seals theconnection section 370 between the element-side AC connection terminal320D and the AC wiring 320A. This will further simplify themanufacturing process, thereby improving the productivity.

(9) The module case 304 includes one opening face on which the insertionslot 306 is formed. Then, the module case 304 is configured in which theconnection section 370 is arranged inward of the module case 304 fromthe opening face and the DC positive wiring 315A and the DC negativewiring 319A extends out of the module case 304 from the opening face.This will protect the connection section 370 by the module case 304.

(10) The power module 300U further includes the wiring insulationsection 608, which supports the DC positive wiring 315A and the DCnegative wiring 319A, and the wiring insulation section 608 is to befixed to the module case 304. This will protect the connection section370 from stress occurring when incorporating the power module 300U intothe inverter circuit 140 so as to connect the DC positive wiring 315Aand the DC negative wiring 319A with another device.

(11) The second sealing resin 351 is to be filled in a space between theinside of the module case 304 and the first sealing resin 348. This willreliably fix the module primary seal body 302 in the module case 304.

(12) The power module 300U includes the IGBTs 328 and 330 constitutingthe upper and lower arms, respectively, of the inverter circuit 140 andincluding the control electrodes 328A and 330A, respectively, theelement-side signal connection terminals 327U and 327L being connectedwith the control electrodes 328A and 330A, respectively, included in theIGBTs 328 and 330, the element-side DC positive connection terminal 315Dand the element-side DC negative connection terminal 319D, beingconnected with the positive electrode side and the negative electrodeside, respectively, of the series circuit 150 constituted with the IGBTs328 and 330 and supplying DC power to the series circuit 150, and theelement-side AC connection terminal 320D for outputting AC power havingbeen converted from DC power by the series circuit 150. In the powermodule 300U, each of the element-side signal connection terminal 327U,the element-side signal connection terminal 327L, the element-side DCpositive connection terminal 315D, the element-side DC negativeconnection terminal 319D, and the element-side AC connection terminal320D is aligned. In addition, the control electrodes 328A and 330A,included in the IGBTs 328 and 330, are each arranged in a positionshifted to either one side relative to the central lines 376 and 377,respectively, which are perpendicular to the alignment direction of eachof the terminals. In addition, the element-side signal connectionterminals 327U and 327L are each arranged on one side where the controlelectrodes 328A and 330A are arranged in the IGBTs 328 and 330,respectively, the element-side DC positive connection terminal 315D isarranged on the other side where the control electrode 328A is notarranged in the IGBT 328, the element-side AC connection terminal 320Dis arranged on the other side where the control electrode 330A is notarranged in the IGBT 330, and the element-side DC negative connectionterminal 319D is arranged between the element-side AC connectionterminal 320D and the element-side signal connection terminal 327L. Thiswill minimize the length of the bonding wire 371 which connects thecontrol electrodes 328A and 330A with the element-side signal connectionterminals 327U and 327L, respectively, thereby improving the reliabilityin connection. In addition, the terminals are collectively arranged soas to achieve reduction in size of the module primary seal body 302, andthus the power module 300U.

The above explanation is merely an example and the present invention isnot to be limited to the above embodiments.

What is claimed is:
 1. A semiconductor module comprising: a first powersemiconductor element having a first surface and a second surface; asecond power semiconductor element having a first surface and a secondsurface; a first conductor plate disposed on the first surface of thefirst power semiconductor element; a second conductor plate disposed onthe second surface of the first power semiconductor element; a thirdconductor plate disposed on the first surface of the second powersemiconductor element; a fourth conductor plate disposed on the secondsurface of the second power semiconductor element; and an intermediateelectrode which is integrally formed with the second conductor plate,extends toward the third conductor plate, and is connected to the thirdconductor plate, wherein a first main surface of the first conductorplate and a second main surface of the third conductor plate arearranged on a same plane, the first main surface of the first conductorplate facing the first power semiconductor element and the second mainsurface of the third conductor plater facing the second powersemiconductor element.
 2. The power semiconductor device according toclaim 1, wherein the intermediate electrode has a bending portion whichis bent toward the third conductor plate from the second conductorplate.
 3. The power semiconductor device according to claim 2, wherein athickness of the intermediate electrode is formed smaller than athickness of the second conductor plate in portion to which the firstpower semiconductor element is connected.
 4. The power semiconductordevice according to claim 1, wherein the first conductor plate, thesecond conductor plate, the third conductor plate, and the fourthconductor plate are fixed with a sealing resin, the second conductorplate is exposed from a surface of the sealing resin, and theintermediate electrode is not exposed from the sealing resin.
 5. Thepower semiconductor device according to claim 1, wherein on the sameplane the first conductor plate does not overlap the third conductorplate.